Figure 2

The figures represent attractivity of the equilibria of system ( 1 ) when (clockwise): (a) ${\mathit{\beta }}_{\mathbf{1}}\mathbf{-}{\mathit{A}}_{\mathbf{1}}\mathbf{\le }\mathbf{0}$ and ${\mathit{\gamma }}_{\mathbf{2}}\mathbf{-}{\mathit{A}}_{\mathbf{2}}\mathbf{\le }\mathbf{0}$, (b) ${\mathit{\beta }}_{\mathbf{1}}\mathbf{-}{\mathit{A}}_{\mathbf{1}}\mathbf{\le }\mathbf{0}$ and ${\mathit{\gamma }}_{\mathbf{2}}\mathbf{-}{\mathit{A}}_{\mathbf{2}}\mathbf{>}\mathbf{0}$, (c) ${\mathit{\beta }}_{\mathbf{1}}\mathbf{-}{\mathit{A}}_{\mathbf{1}}\mathbf{>}\mathbf{0}$ and ${\mathit{\gamma }}_{\mathbf{2}}\mathbf{-}{\mathit{A}}_{\mathbf{2}}\mathbf{\le }\mathbf{0}$, and (d) ${\mathit{\beta }}_{\mathbf{1}}\mathbf{-}{\mathit{A}}_{\mathbf{1}}\mathbf{>}\mathbf{0}$ and ${\mathit{\gamma }}_{\mathbf{2}}\mathbf{-}{\mathit{A}}_{\mathbf{2}}\mathbf{>}\mathbf{0}$. The dark and light lines respectively represent equilibrium curves $E_1$ and $E_2$.